During production of contact lenses, in particular but not only during manufacturing of single wear contact lenses in very large batch numbers, reusable molds can be used which typically comprise two molds halves essentially made of glass, e.g. of quartz glass or of glass called BK7 available from the company Glaswerke Schott, Mainz, Germany. It has shown to be advantageous when the glass molds or mold halves, respectively, have been exposed to a plasma, e.g. an oxygen plasma, prior to using the molds in production. This is described in more detail, for example, in EP-A-1 332 856.
The glass molds or molds halves, respectively, may be arranged in a plastic sleeve which helps in properly centering the mold halves during closing of the mold, as this is described, for example, in WO-A-99/20455. Exposing the molds or mold halves including the plastic sleeve, however, may result in that the molding surface of the glass molds or mold halves are contaminated with plastic from the sleeve during plasma exposure which may adversely influence the quality of the contact lenses to be produced. Also, exposure of the plastic sleeves to plasma adversely affects the plastic sleeves through oxidation, for example the plastic sleeves may become more brittle etc.
Accordingly, it is an object of the invention to suggest a method and an apparatus which prevent possible contamination of the molding surfaces of the glass molds during their exposure to plasma on one hand and on the other hand eliminate or at least greatly reduce exposure of any plastic components to plasma.
This object is achieved by an apparatus, a carrier and a method for the plasma treatment of molds as they are characterized by the features of the respective independent claims. Advantageous embodiments of the apparatus, the carrier and the method are the subject of the respective dependent claims.
In the following, when the term “mold” or “molds” is used it is intended to include the term “mold half” or “mold halves” wherever this is appropriate.